Sunday, September 16, 2007

Personally I find nothing more thrilling in gardening than the successful propagation of plants. While growing from seed is pretty good, especially for perennials, taking cuttings of plants is positively magical. It is, after all, cloning.

This year I have taken cuttings from two shrubs. The first is a friend’s red-flowering Weigela, which blooms at least twice each summer, fairly unusual in Weigelas. I don’t know if it’s a known or named cultivar, or a lucky find in a seed-raised plant. (Weigelas aren’t known for great foliage or branch or fruit interest when they’re not in flower, so rebloom is an important feature.) The cuttings were taken in late June. I cut off several branch tips, keeping them in a Ziploc bag with a damp paper towel for a few hours before getting to my garden.

Most of the Weigela cuttings had two leaf nodes. For each, I made a fresh cut just below the lower leaf node, removed the lower leaves, and trimmed back the upper node to two half leaflets (i.e., I cut each leaflet in half). I used a single-edge razor blade, but a knife will do if it is sharp.

I inserted the cuttings in some seed starter mix, in 3-inch Jiffy peat pots, and kept them damp and under a clear plastic cover, with perhaps an hour of morning sunlight each day. Basically a cutting is a race to grow roots before wilting or a fungus takes over, but you can’t try to rush the growth with heavy sun or fertilizer, or you will uniformly fail.

As soon as a cutting starts visibly growing, it is also growing roots, and it can be put where its humidity-sealing cover is removed gradually, perhaps an hour a day for a few days, until it is always uncovered. Once uncovered, you will have to water or mist it daily. And then you put it into successively sunnier locations until it is acclimated to where you want to plant it, and you’ll only have to water when the soil is dry.

As of now I have three strong Weigela plants, which have rooted and more than doubled in size, four more plants whose future is in question, as they haven’t grown and are looking rather tired, and about four which succumbed to rot. (You must throw out any rotting ones lest the fungus or whatnot spread to the others.)

The beauty of cuttings is that with access to a healthy bush it’s trivially easy and cheap to take a dozen of them. And with most plants, most of the time, and a modicum of care, that’s usually enough to guarantee a few successes. If you can get Rootone®, TakeRoot® or a similar hormonal rooting product, that often increases your success rate to a clear majority, but with some plants like willows (various Salix species) you can put a stick into the ground just about anywhere, even upside down, and be almost guaranteed of success. (They are harder to keep alive when rooted in a pot.)

Weigelas aren’t quite as vigorous as willow cuttings, but they are known to be easy, so I didn’t bother tracking down Rootone, which I was surprised to learn is not carried by all garden supply stores and nurseries. Of my three successes, I put two into my garden in late August. The third is in a fairly large (perhaps 5-gallon) plastic pot which I aim to bring inside for the winter and place in a window. Hopefully at least one plant will survive cold, snowfall, and/or neglect (the oversized pot will last longer between waterings), making it to spring, and clear sailing for a shrub.

This year I purchased the rose known as ‘The Fairy’ – a smallish but very healthy, adaptable and long-flowering rose with many small pink double flowers. It is known to root fairly easily, with spreading canes which often layer spontaneously where they touch the ground. The Fairy dates from 1932, and so is not under patent.

On the 13th I decided to experiment with this plant, to see if I would have any success under, if not the worst of conditions, then certainly a half-assed attempt to maximize success -- late in the season, with no rooting powder, and using no cover, relying instead on shade, cooler weather, and the harder wood of later-season cuttings being more resistant to wilting.

I trimmed off a disproportionately long cane (partially seen in the top center of the first photo) and made about ten cuttings.

I had used a gloved finger to pop the thorns off to the side, making the material easier to handle, but while the Weigela had been softwood in late June, this roses’ hardwood cuttings were, indeed, quite hard to slice through with a razor blade. I was almost surprised I didn’t get myself sliced in the process. Note the sticky pad, which is a 3-inch square; a fully prepared cutting is to the left of the pad.

Most of the cuttings have three nodes; some have two. I removed the lower two nodes’ leaves, and half or more of the leaflets in the top node, and inserted most of the cuttings, untreated, into the ground. This was in a very well-drained area, a raised bed, which I had double-dug and amended with compost a month previous when I was planting a (rooted) Weigela. It is important that the cuttings area be such well-drained and yet moisture-retaining material, free of competing roots, loosened, but also firmed down. Ideally, experts such as Christopher Lloyd recommend a mix of 1 part loamy soil, 2 parts peat moss, and 3 parts coarse sand or grit (1/16 to 3/16 of an inch).

Four of the cuttings I inserted along the rim (shaded side) of the large pot with the rooted Weigela in the middle. This pot is still outside, getting morning sun on the Weigela, but it will go inside for the winter.

Certainly these late, unbabied rose cuttings are at greater risk than the already-rooted Weigelas. But even fully rooted cuttings are not as winter-hardy as larger, established plants. Altogether I will be happy if I get at least one Weigela and two roses to survive into next year’s growing season; after all, they cost me nothing (I did use about $6 worth of supplies I already had, as noted). I may put something cage-like on top of the outside plants so heavy snow won’t crush them.

How late in the season can you do all this? Softwood cuttings are best taken by early July, so as to be strongly rooted by end of season. Hardwood cuttings are supposed to be doable even into November. But in that case, you can’t expect any growth or rooting until spring. (The cuttings will probably survive, dormant, since having no leaves that late they won’t be losing much moisture.) The limiting factor then may be frozen ground. You could, if planning cuttings, prepare the ground ahead of time and keep it unfrozen with a thick layer of mulch.